This invention relates generally to a portable foldable stand for supporting a heavy article, more particularly to a portable foldable stand which is convenient, safe, and easy to unfold from a storage position and raise to an operating position, and then to reflold to the storage position.
While the invention may be used to support any type of article, it is particularly useful in supporting and transporting a portable pipe threading machine which is quite heavy and cumbersome to handle. Plumbers move from one job site to another, and the threading machine is liftedn on and off a truck frequently.
Collapsible carriers for such an application have been proposed in the past, as typified by the device illustrated in U.S. Pat. Nos. 4,611,823 and 4,728,118. However, these carriers employ dangerous exposed mechanical tension springs which produce abruption controlled folding and unfolding motion.
U.S. Pat. No. 4,558,648 generally discloses some advantages of using gas spring cylinders in scissor mechansim for raising and lowering a platform. However, the overall construction shown therein differs substantially from and is much more complex than this invention.